Toyota 8AT transmissions allegedly jerk, lurch and hesitate in Highlanders and Siennas.

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Toyota 8-Speed Transmission Problems Lead To Lawsuit
Toyota 8AT transmissions allegedly jerk, lurch and hesitate in Highlanders and Siennas.

— Toyota 8-speed transmission problems have caused a lawsuit that includes Toyota Highlander and Toyota Sienna vehicles equipped with direct shift 8AT transmissions.

According to the lawsuit, the 8-speed transmission, also known as the UA80, causes harsh or delayed shifting, delayed acceleration, hesitation, jerking, unintended acceleration, lurching and excessive revving before upshifting.

The 8-speed transmission problems allegedly occur in 2017-present Highlanders and Siennas, and the plaintiffs who sued claim Toyota has actively concealed defects in the 8AT transmissions.

The lawsuit says that since their release in the 2017 model year, the Toyota Sienna and certain Toyota Highlanders have been equipped with Toyota’s UA80 transmissions. The plaintiffs claim the automaker also uses specific model numbers UA80E and UA80F for the 8-speed transmissions.

In addition, UA80 is used for 6-cylinder vehicles and UB80 is the designation used for 4-cylinder vehicles, and UA80E is the model number for transmissions in forward-wheel-drive Highlanders and Siennas. UA80F is the model number for transmissions in all-wheel-drive Highlanders and Siennas.

Florida plaintiffs Dennis and Deborah Murphy purchased a new 2018 Highlander XL and within a week the vehicle allegedly experienced "hesitation and surging when driving at low speeds, in stop-and-go traffic and when accelerating to join a traffic flow."

In September 2018 when the vehicle had about 2,000 miles on the odometer, the plaintiffs took the vehicle to a Toyota dealership which performed diagnostic tests and found the vehicle was performing normally.

In January 2019 with about 8,730 miles on the odometer, Mr. Murphy took the vehicle to a Toyota dealership and complained the vehicle "demonstrated erratic throttle responses at low speeds, hesitating and exhibiting surges when lightly applying the throttle at parking lot speeds."

The dealer allegedly couldn't find any problems with the Highlander and therefore no repairs were made.

In April 2019, Mr. Murphy returned the vehicle to the dealership and again told technicians the vehicle was "demonstrating erratic throttle responses, stumbling and surging at low speeds."

The dealership couldn't find any problems, but the lawsuit alleges a senior technical service adviser admitted the 8-speed transmission problems "were common to Highlanders and other Toyota models and were well-known to Toyota and its dealers."

Then in May 2019, Mr. Murphy returned to the dealership and complained about continued transmission problems, telling dealer technicians the vehicle needed to be repaired, or Toyota should buy back the vehicle.

The dealership performed no tests or repairs, but the plaintiff was told a Toyota representative needed to inspect the vehicle, something that occurred when the vehicle had about 11,930 miles on the odometer.

A "Toyota District 2 Fixed Operations Manager" test drove the vehicle but made no repairs, reporting that he “found it to perform like a known good vehicle” and did “not exhibit any warrantable concern.”

“[T]oday’s vehicles . . . are driven by wire which means they do not have a throttle cable so they may exhibit very slight lag due to the ECM processing. The current eight speeds transmissions are gear to keep the engine in an optimum operating condition which may not meet the customers desired performance but in every case, a little extra pressure on the gas pedal improves responsiveness and customer satisfaction can usually be obtained.” - Toyota manager

In October 2019, the plaintiffs took their vehicle to a different Toyota dealership and again complained about "erratic throttle responses at low speeds, stumbling, and exhibiting surges when lightly applying the throttle at low speeds."

The Toyota technician allegedly said the 8-speed transmission problems were “caused by: internal failure on transaxle assembly” and consequently “replaced [the] transaxle assembly and associated parts per bulletin T-SB-0160-18.”

However, the plaintiffs claim the Highlander continues to hesitate and surge when driving at low speeds, in stop-and-go traffic and when accelerating to join a traffic flow.

And adding to their problems, the plaintiffs allege the vehicle is even worse now since the transmission transaxle assembly was replaced.

The class action lawsuit references technical service bulletins (TSBs) Toyota issued to dealerships concerning the 8-speed transmissions.

Toyota issued T-SB-0187-17 in February 2017, titled “High RPM Shift Point,” which said some 2017 Sienna vehicles may experience the following conditions:

  • Lack of power from stop
  • High RPM shift points at 2 – 3 shift
  • Hesitation in lower gears
  • Holds gear too long

Toyota dealerships were told to perform a software update to modify the powertrain control module logic for the Siennas.

A month later Toyota issued T-SB-0194-17, titled “Lack of Power/High RPM Shift Point/Hesitation” for the 2017 Highlander which said the vehicles may suffer from:

  • Lack of power
  • High RPM shift point at the 2 – 3 shift
  • Hesitation in low gears

Again, dealers were told to update the powertrain control module software.

In 2018 Toyota issued TSB 0160-18 titled, “Transaxle Whine Noise, Harsh Shift, MIL ON, or Reduced Power” that applied to the 2017-2018 Toyota Highlander and Toyota Sienna.

However, this time Toyota told technicians to replace the transmissions with remanufactured transmissions.

According to the class action, the alleged 8AT transmission problems make driving dangerous and a hazard to occupants in vehicles and surrounding property when the 8-speed transmissions hesitate, jerk, lurch and suffer from acceleration issues.

The Toyota 8-speed transmission lawsuit was filed in the U.S. District Court for the Central District of California: Murphy, et al., v. Toyota Motor Sales, U.S.A., Inc., et al.

The plaintiffs are represented by Berger Montague PC, Glancy Prongay & Murray LLP, and Greenstone Law APC. has complaints from owners of the Toyota models named in the transmission class action lawsuit.


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